Radio navigation device



Oct. 7, 1952 G. 1 LANG 2,613,351

RADIO NAVIGATION DEVICE i Original Filed Aug. 7, 1943 FIGA 2 A 'AVA Patented Oct. 7, 1952 Gregor L.,Lang, Suffield, Conn.,f assignor to The Y Sperry Corporation, a corporation of Delaware` 4 Continuation of .abandoned application Serial N o; Y 497,786, August 7, 1943. This application May 18, 1948, Serial No. 27,732` t 13 claims. (ci. 34a-107) patent application Serial No..497,786, led August 7, 1943, now abandoned. ,f

Although the invention is susceptible to use with various typesof land vehicles and marine vessels-.the invention is particularly applicable to aircraft and for convenience-:isherein described as ,applied thereto. ,It is common practice for aire craft to fly exclusively by instruments along radio ranges or beams of distinctively-modulated overlapping lobes of radio frequency energy extending from a transmitting station.. The pilot may y his` craft along a ,course represented by the equisignal axis of the overlapping portions, and since the energy in each lobe is distinctive from the othendepartures to the right or left'of the course may be readily identified. Similar radio beams have been utilized for vinstrument landing` pur# poses,in `which event the equi-signal line'or axis extends at a slight angle to the` horizontal to form a glide ,path-deviations then being detected in a f Verticalplane.`

It ,often becomes necessaryfor` a pilot to maneuver his .ship onto a course defined by such a glide path ordirectional radio beam from a posi` tion `laterallyzdisplaced therefrom.` The pilots deviation from 'the course customarily is mani--Y fested by a characteristic audible-signal, and usually also by a visualindicator, such-as an electric meter havinga pointer denoting the direction and extent of the displacement. .Upon learning of a deviation from course, the pilot normally `Varies the heading of;his craft to a new heading,` and proceeds Until the audible or visual indications are lrestored to normal; Thus, `if the :visual indicator gr left-rightmeterl denotes that the craft has1 veered tothe right from lits course, the pilot applies left rudder tochange the heading of the craft ina direction to restore the craft to its course, `and then observes the gradual restoration of the meter pointer `to a zero position, at which time the craft `vvill have e reached y the l equi-signal line of the beam. However, unless precise and prompt correction lof heading` is then made, the craft will overshoot the course,'requiring the pilot to attempt oncemore to choosel a heading atan angle .to course in order to4 return tothe path. The tendency, therefore,isfor the craftto hunt onopposite sidesof-the beam in a manner Vthat isdisconcerting to the pilot, since. itis difticult to orient the craft properlyrelative to the course direction at the moment that the craft reaches the course. The problem is 'to'rreach an on course position with a simultaneous correct hasta 3some skilled pilots lco mpensatesomewhat for the effect' of hunting y` progressively; Varying the craft `heading in accordance -with the changes in the -meter indicationsybut such a procedure involvesfconsiderable skill and experienceabased on` correlating the successive craft `headings: With the rate at'lwhich the visual indicator changes, requiringisome mental operations on-the partiof the pilot andthus being subject `to erroryanddistracting the pilotfrom other duties. l A The present invention relievesthe pilot of ythis burdenby incorporating, in themeter indication,

a function of the rate at which the detectedv dis.- placement l is` changing: and accordingly; the` rel'- ative` rate `at which .theaircraft is, approaching or leaving .its'course The improved instrumentv thereby lguides the pilot as to theheading to be h'eldfby the craft `to bring it along ai curvilinear pathinto the course;v allowing relatively inexpef rienced pilots to avoid overshootin'g; "andfitl provides a ready and positive indication of the suc'- cessive headings to befheldbythe craft so as" to approachtthe course in a generally tangentialor asymptotic manner.' C f n Theprincipal objects of the present invention arertov providev 'an improvedindicatorfor denoting 'deviations from theoptimum instantaneous headings of a craft :relative to achosencourse-; to provide a visual or other typesindicator denotingWhen a craft ismaking a proper asymptotic or fdead-beat.A 'i approach ftofa given course; nto

provide' a `neutral indication tolthef pilot even` sensitive to either or both'displaceinent andvtime' rate of A4change of displaeementyandto lprovide means foradjusting thesensiti'vityf of suchan instrument to either'or boththe displacement and rate signals. These and other objects of the in` n vention Will become more apparent from tlfiefol-` lowing description and from the" accompanying drawing describing various lenribodiinents ofthe present invention. V 9' f In thedrawing, l e 1 Fig. 1 is a diagram of a radio beacon orcourse formed by the line of symmetry of ing directive radiation patterns orbeams; e

- Fig.` 2 is a diagram illustrating 4the visual indil` c'ation'acordedV to Aaircraft pilots with vfornerv and' the present improved systems, respectively;

Fig. 3V is a wiringdiagr'am of-a circuit rating principles4 of the :invention and incorpotvs/o` intersect-- on an initial heading aimed steeply-to intersect the course. As the displacement signal. decreases, the rate or ,direction signal must be.correspond. ingly` decreased by` modifying the craft direction to decrease its angle relative. tothe course; to maintain a balancedcondition with the pointer I I z substantially neutrally positioned. The displacement signal may be derived-inlany `con` ventional-.manner according tothe `type of course signal radiated.fromtheltransmittene. g.; as shown in the W. G. Hardinghet al. Patent No. 2,201,174; Thepathsl and I thus curve gradually and approach the'course Cin` asubstanf tially tangential r asymptotic manner if the pilot .iiies the airplane. so as `to maintain the meter reading` neutral at al1 times. The curva- Y tures of the paths 6 and 1 depend upon the initial adjustment of `they apparatus, `as will'become apparent. M 1 ,.1 Fig. Bdiscloses a typical circuit by whichthe foregoing maybe obtained. `VThe circuit come prises .the `audio output portion of an aircraft receiver of the general type shown in said Re, issue `Patent No.. 22,484, and in;` said Patent No.

2,439,044. Output transformers ,I2and I3 haveV primary windings` I4 that connect respectively y with the'output` of the usual filtercircuits (not shown) `for segregatingthe` modulation `componentsof the; respective beamsB. The signals appearing` across the `secondary windings of the transformersv I2 and I3,- oppose one another across` dual potentiometers I5 and I6 ,having ganged sliders I 1 and I8 whichmove in balanced relation along ,the resistance elementspf4 the potentiometers. 1 The signal'developed across the sliders is the difference'signal or net ,displacement signal, which varies `,asl the Alateral distance of ;.the craft from the courseCxdei-lned'by the beams, having a polarity determined Y,by lthe directionrof the :displacement from course., Thev displacement signaliiswapplied tov the meter M after being rectified in thermionic tubes I9 and 2I.

The circuit of Fig..3 Vcomprises generally a rectifier stage 24,; rate taking stage 25, 25. `and 26, 26',` a cathode follower stage 22, 23 anda mixer stage I 9 and 2|, the output of which is connected tothe indicating meter, II.` "Ijhe vdis-.- placement signal appearing at the outputs I1 and la for potentiometers' l5 and Is isrectified through adual `diode 24. Smoothing circuits 29,3LI and 3l 'are provided for smoothing `theD. C. output of` rectifier 2t. In` accordancewith the` principal feature of the'present invention, the rectied displacement signal is applied to an impedance-reactance rate takingnetwork such as theresistance-capacitance' network 25,Y 25' 'and 26, 26? 'the "output vof which acrossv resistances 25' and 26' is igiroportionalto the timeratefof changey of the input displacement signal and lis applied toLtlie grids of cathode followers`2`2."23.` `From one lpoint of view thejoperatiOn 4of the rate taking circuits maybe described as follows. The cndensers and 2E of the RCnetworks, havingl anirnpedance inversely DI'ODOI'tiGaT ,t0 fl" quencyi,will pass only anincreasing ordecreas-l ingsignal voltage and the voltage .jimpressed across the resistances 25' and 26 will be `proportional to"v the rate'at which the signal'volt-v agincreasesor decreases. On the other hand, when the signal`voltage atA the condensers- 26"- is Vconstant or'not changing.' no `voltage `will be impressed across theresistan'ces' 25and 26":

The Vvoltage across resistances 25'vandf2`5f, which sproportional `tothe rate of change of the ldis-1 placement 'sig'nal voltagefis appliedfto `the ,grids of cathode" followers 22 .l `23.- i The@ cathodes off i ment, fromthe meterindication.

cathode: followers 2:2 and `23 Aare connectedrespectively to the cathodesof apair of=miXer tubes I9 and ..2I, suitable cathode follower `circuits"".'2 being provided. The displacement signalsfat -Il'l and I8. are impressed, through' suitable lcon? pling condensers, upon the grids of tubes` I9l and 2'I The displacement.signalandithe rate signal are combined or mixed' in opposing sense "and the resultant'signal is applied to the indicating meterM.=` "f The anode lelenientsfof both pairsofi-tubes I9, 2|, and: 22', `23, lare l connected in `parallel and are-supplied .with positivedire'ct' voltage through'a potentiometer y21 connected as shown in Fig. 3. The cathodesof-thetubes I9v and`22l are connected together, as are the cathodes' `ofkthe tubes 2l Vancll'lfrthe r'espectivepars beingcon-f nected tol themeter Mthr'ough asui'table defi'ec# tion controlf're'sistor 28; W In operation, .thelcircuit vshown 'iniFig v-3 separates thewdisplacement signals fromY the-time rateof changeof displacement signals appearing on the grids of tubes`22land 23. The signals are mixed -before being applied to `the meterv M in suchaE-wayl that rate signals produced'by motion of the craft toward the course subtract from the amplitude of the-displacement signal; The sharpnessot thean'gularlapproachto the course depends uponthe krelative strength ofithe rate-and displacement signals and may be ad justed `by 'controllinglthe position ofthe slider of potentiometer f2'1.,f=or`1byanyf other `manner varying the' gain 'ofl the circuits producing the respective signals.` `For `a* sh`ar'p approach 'as along. jthe` line 3; `the gain off'theirate signal circuit 4is made low, requiring adlargeftime rate of changel of the displacement signal to 'counterbalance the'displacement signal. Convers'ely;{for a 'shallow approach as along the path al small timelrateFiori-displacement signal is" amplie'd highlyY so as to equal the displacement-fsignal.' The tubesl 2l, `22-and 23'ope`rat a's'a-mixer, with the signals subtracting when-the craftapproaches the course and adding when thelcraft leaves the course.

craft moves away from4k the' course.

vSwitches 36 may" be provided to render the` indicator responsive to but one of the separate circuits, whereby the pilot 'may at anyV time de`` termine either absolute rate or absolutedisplace#v Fig. 4 illustrates a simplification ofthe circuit shown in Fig. 3.` Thefsec'ondary windings 2D of' through lwire 35. The opposite side of each rectier/33, 34fconnects with the grids 36andi`31-of y a dual triode 38 through a pair of variable resistances 39 `and 4I, across which a rcomponent of the displacement signal will appear, and a pair of Vvariable time-constant rate circuits 42, 41 and 45; and 43, 48 and 66.' Again, the'catho'des of the dualA triodelv are connected to the meter '.M through a center tap resistor M whichv provides a load across which the combinedlratev and displacement signalsmay be developed.` The valuel of the' displacement` signal maybe varied byvaryingthe impedance of the `resistors '39l and 4I; lThe rate circuits 42, 4'! and 45; and 43,

, 7y l! fanden, lcmcraie in the; same manner as fthe satewcircuitsdescribed-in"Fie;3.: i f 1 giTberpperaticn- 'of 1the.;:arrangement.'shoum in Ri isfas `follcwii:fAssuming thatfthefresistors una; .f :have aan lnfiniteresistance; lthe l'dis- Plwementgslgnals arerimpressed 'acrossgthe @condnersfz; andior'iilsfiend'fu :ndZmfIIMas the -esistances 4,5-, 46 ,which cir.- smits-1 `explained iabove.; 4derive a; :signaliproportional to the time rate of change oivilrieftlis-V placement signal. fIl'l'crefm'e,y fthe meter Mibemes-isensitive .onlyzftof timef rate, of. rchange of th f fective- -displitcement` signal.` ;Gonvers'ely', capacitors A12 J.and `4:I;.`fm:14f andI :4% ,tb hvcs'irxniie iximexiax1cm` the -.displacement vsignal iiiinmress'ed acrosszthe.l resistencias as, 45 and-54:1, I6.'Y V@Since the capacitance in the circuits isi-1nno ,rate :of vchange of displacement fsm-ns1 will be derived and the m'eterJM vindicaties onlythe displacement signals Hence.. byvaryingxhe relation. between y9111i resistance andi-'the capaci tance- Jin, yboth fcircuitsf v--tlhenefl-ec1i 'lof f disp'laicement-signals and wie signals on. tnewmeer M` may f-be controlied.v Fitomxthe above', iit, will :be ngtedfthat the proportional; amount lof i displaceb 'ment fsignal vamplied ic the grids of, ltube 3B; 'as

ccmnared Lto the ratesignalsy A'may :be: variedgihy c pntrolling; Ithe value Yof #che yl-iesistance s:;3 9 and; 4.1,; and valso thai; theses-relative signall values be ccntrolled .by vanying fthe timecnnstant Vlofthe iciiicui-i, fasby Vincreasing -the effective are sc-v combined.. as tcA sign. as; to, buck Y Will equal the-magnitude -Qf .the dsplaqexneni;

@QW dQSCrintOnQI-- Shawl-1in the accompanying dirawi .n Shall beintcrnreted as illusimtive fand; mfinnl-imting-Lsense.

plication. contains @mmm with thev :applications Oli-f,allv'iinslcwY Blmes.fQr-Eadio-N ble-Craft.. Serial. uN

15 A navigation-deviceicitfiridicaiing prcnn. heading'ofeaniairraft whenffiyinigmcnrvedpath. ladng, substantially vningen-t:'nii-ly mi a straigmf @ourse 'lying-,kalm fthe equifsisnalzllmecf :az-mmf uf overlapping disiineiivfekie.insdulssieclgdiizccffY ticnai radio; beams-- comprising.: meanszgior derin- L sdifferencersignalfesafuncm cfthe differs;

cfeiriaaziin eaiuires i for enceinaniintmisity charmcteristicfoisid'rcespe tive; beams.: means fcnntrlled gray; said, difference signalntorzxierivingna', rateisignlv'lpizoportionail'th theztim'e maize roffcharngioffasaid diieizexmelfsigrml,v

aan indicating sii-istmimentuiesponsive tos said y dinieiiencesignalianlituamfxatesigml.' f A .2. Afnavigaiiimidevicertim.Lindicaiingl 'mper headingfcf aireralft when ia: rciuvedmath. leading :substnimmfitngentially :mia ."stmiht course lyinglialongifith'e '.eriuiesigfnaisli'nmf a.4 ofV avenlappingigdistincbivelymcdulted ,dined-,- tional radio beams; cnmpizisigtmeans icisid'ettv ingfiaxdi'lerexice; Signat-asini iimctiqnf, ithe terence'ftin; ixitensity..cha,rateiisticfxof respective be'ams, means cmitmliemibyifsadd ference signal Ioriiierivingimzmte; signalpropoxi- Ithfel .timeH weites-of.' hangeof: :s said dierence.. signal; fandf ian' lindicating instnumeni.

responsive toA said difference signal and 9 time rate of change of said nrst signal, and means for algebraically combining said signals and supplying an indication to the pilot proportional to the resultant signal.

6. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio beam-defined night path, said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said nrst signal, amplifier means for combining said signals and supply-ing an output proportional to the algebraic sum thereof, and a meter of the center zero-reading type connected to receive the output of said ampliner.

7. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio beam-denned night path, said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said nrst signal, an indicator connected to be controlled in accordance with the algebraic sum of said signals, and means for varying the responsiveness of said indicator to said second signal.

8. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio beam-defined night path. said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said difference signal for deriving a second signal proportional to the time rate of change of said first signal, an indicator connected to be controlled in accordance with the algebraic sum of said signals, and means for varying the responsiveness of said indicator to said nrst signal.

9. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio beam-defined night path. said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path. means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said nrst signal, an electronic mixer for algebraically combining said signals, and an indicating means operated in accordance with the output of said mixer.

10. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio-beam-deiined night path, said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said first signal for deriving a second signal proportional to the time rate of change of said first signal, means for combining said signals such that said signals are subtractive when the craft approaches the night path and additive when said craft departs from said night path, and an indicating means responsive to the output of said combining means.

11. An indicator system for denoting tothe path, means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said first signal, means for combining said signals such that the two signals are subtractive when the craft approaches the night path and are additive when the craft departs from the night path, indicator means responsive to the output of said combining means, and means for varying the sensitivity of said device to at least one of vsaid signals.

12. An indicator system for denoting to the pilot of an aircraft correct instantaneous headings of the aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along a radio beam-denned night path, said system comprising means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said nrst signal, summing means connected to receive both of said signals for providing an output proportional to the algebraic sum thereof, an indicator connected to receive the output of said summing means, and means for rendering said indicator unresponsive to one of said signals.

13. In a system for determining correct instantaneous headings of an aircraft in order to effect an asymptotic approach to and maintenance of night thereafter along-a radio beam-denned path, means including a radio receiver for providing a nrst signal proportional to displacement of said craft laterally from said path, means controlled by said nrst signal for deriving a second signal proportional to the time rate of change of said nrst signal,and means connected to receive said signals for supplying an output proportional to the algebraic sum thereof.

GREGOR L. LANG.

REFERENCES CITED UNITED STATES PATENTS the Number Name Date Re. 23,066 Moseley Dec. 21, 1948 1,315,539 Carson Sept. 9, 1919 1,703 317 Minorsky Feb. 26, 1929 2,099,536 Scherbatskoy et al. Nov. 16, 1937 2,122,091 Davies June 28, 1938 2,257,757 Moseley Oct. 7, 1941 2,266,410 Busignies Dec. 16, 1941 2,322,225 Crane et al June 22, 1943 2,372.185 Wittkuhns Mar. 27, 1945 2,423,336 Moseley July 1, 1947 2,439,044 Ferrill Apr. 6, 1948 FOREIGN PATENTS Number Country Date 516,567 Great Britain Jan. 5, 1940 

